The purpose of this proposal is to investigate the influence of neighborhood context on initiation and maintenance of adolescent substance use. It is well known that neighborhood context influences individual behavior but it is less clear how specific neighborhood conditions - disadvantage and instability - shape adolescent substance use. We will explore cross-sectional associations among indicators of neighborhood disadvantage and instability (poverty, female-headed households, unemployment, residential stability, racial heterogeneity and crime) and drug involvement (initiation, alcohol use, marijuana use, illicit drug use, mean frequency of use, drug use control, and adverse drug consequences) and longitudinal effects of change in use over a 9-month period. Specifically we ask: 1) Does neighborhood disadvantage and instability have a direct and/or moderating effect on adolescent drug involvement net of individual, family, and peer characteristics? 2) Does neighborhood disadvantage and instability have a direct and/or moderating effect on change in drug use net of individual, family, and peer characteristics? To address these questions multiple data sources will be linked together. The base dataset comes from the Reconnecting Youth (RY) prevention research studies, funded by NIDA, DOE, and CDC, providing a random sample of high school aged youth, stratified by high-risk, in the Seattle metropolitan area. The secondary data comes from the United States Census and the Seattle-area police departments. Individuals in the RY dataset will be linked to their census tracts and then local characteristics at the census tract-level will be added. Multilevel techniques will be used to assess the impact of neighborhood on substance use and growth in substance use behaviors and adjust for the natural clustering within neighborhoods. Findings from this project will inform future grant submissions to explore the effects of neighborhood context on behavior. [unreadable] [unreadable] [unreadable]